NAME: DiskFree

     USE: Function to return the amount of free disk space, in bytes, of
          the specified drive.  A numeric value corresponding to the
          desired disk drive is passed to DiskFree, a value of 0
          identifies the default drive, 1 equals drive A, etc.

     DEPENDENCY:  The DOS unit must be used placed in the uses section.

     SYNTAX: DiskFree(DriveNumber);
             DiskFree(Word);